The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Compressors are used in a variety of industrial and residential applications to circulate refrigerant within a refrigeration, heat pump, HVAC, or chiller system (generically “refrigeration systems”) to provide a desired heating or cooling effect. A compressor may include an electric motor to provide torque to drive the compressor to compress vapor refrigerant. The electric motor may be powered by an alternating current (AC) or direct current (DC) power supply. In the case of an AC power supply, single or poly-phase AC may be delivered to windings of the electric motor.
For a single-phase power supply, the refrigeration system may include a run capacitor used to initially store and supply power to the compressor. The run capacitor, however, may become faulty either with capacitance degradation or complete loss of capacitance (i.e., an open circuit condition). For example, capacitance degradation or complete loss of capacitance may occur after a period of use due to aging or overheating. A run capacitor with degraded capacitance may cause the compressor to perform below a desired capacity and/or efficiency performance standard. A run capacitor with zero capacitance may cause a start circuit for the compressor to be open, which could result in, for example, a locked rotor trip of a corresponding motor protector circuit shortly after motor start-up. In such case, the electric motor may not provide the compressor with enough torque to rotate, resulting in no cooling production and in an interruption in operation and use of the refrigeration system. Accordingly, a system designed to predict a run capacitor fault, such as capacitance degradation or complete loss of capacitance, is desired.